Bending process



A. E. VARNER BENDING. PROCESS Jan. 1, 1952 Filed July 19, 1948 s Sheets-Sheet i QITIJ INV ENT OR. fmA/s MmwEE' Jan. 1, 1952 I Filed July 19,1948 A. E. VARNER BENDING PROCESS 3 Sheets-Sheet 2 I N V E N TO R 2w):-flaws (IPA/El? ATTOR YV-A A. E. VARNER BENDING PROCESS 3 Sheets-Sheet 5Filed Jill 19," 1948 INVENT OR. 62105 fmA/s VflRA/El? Patented Jan. I, 1952 BENDING PROCESS Alvie Evans Varner, Laurel, Miss assignor toMasonite Corporation, Laurel, Miss., a corporation of DelawareApplication July 19, 1948, SerlaLNo. 395503 2 Claims. .1

'Myinventionirelates to .aprocess of makingv in- :tegra-l fiberhardboard products which are of angular cross-section.

The principal object of my invention is the provision of a processwhereby such products, hereafter designated angular productsiforshort,can be manufactured substantially free from :cracking, breakage, and thelike. A further ob- .jectis the provision of .such a process whereby.zsuch angular hardboard products can be made from originally.fiatisheets. 7

While my process can be'used onfiber boards which have been previouslyconsolidated or on :sheets in :several :laminations, :it is preferablyapplied to a relatively thickporous blank which,

.although preferably .dried nearly or completely .dry,.has notbeeniprevi'ously subjected .to consolidating pressure andheat, andwhich' will be considerably reduced in 'thickness by conversion to.hardboard throughapplication :of heat and pressure. The porous blanksare about /2 to inch thick and the finished angular fiber board productis about to inch thick. The specific gravity of the blank as about .5 to.7 and the specific gravity product is at least 1 and preferably 1.2.

The first application of the process to such a blank consists inhot-pressing and therebycon- 'solidating the blank locally along anarrow substantially linear region or line where the apex of the angularformation-is to be located. This ini- .tialhot-pressing along suchsubstantially linear region or line is preferably performed in suchmanneras to leave the outer surface of the blank substantially fiatorplanein the neighborhood of such line, while forminga substantiallyV-shaped indentation at the surface which will be the interior surfaceof the product. The material is :thus reduced in thickness to about thethickness it will have in the final product and is corre- 'spondin'glyconsolidated, strengthened, and den- .sified locally along 'the :desiredline .'('see Fig. 8).

The consolidated and .densified linear "portion produced by such localhot-pressing treatment'is so located .thatzit'will :be at :andnear theexterior 'surf'aceof the product, with the interior-side indentationopposite .such :outer consolidated line portion. :In performing thelinear densification along such line with .the consolidated portionconfined principally to that part of the blank which will be "attheexterior of "the product and informing 'the'interior-sicleindentation opposite such locally densified linear portion, the lateral.orlleg portions of *therblank con each side :of such may i'be'slightlycocked -:or bent. into angular of the angular fiber board H orveformation with an :interiorangle of slightly less than .(see .Figs. 4and 8). This slight cooking or [bending is favorable in that .it is .inthe same :direction that the further bending. will be performed lateron.

The :Iinearconsolidation treatment which has been described ispreparatory for bending along the densified line portion .sc provided..This treatment has the effeotof providinga comparatively thin,dens-ified linear exterior portion .between the .lateral :or legportions extending outwardly therefrom at either side, on which thin,linear densified portion the lateral .orleg portions .can be turned-orbent toward one another with practical absence of stretching .at theexterior surface. The interior indentation will permit approachment ofthe lateral-portions toward one another in thebending operation, andthis will avoid interior leverage effects being created in bendingadjacent to the consolidated linear portion which otherwise would tendto produce stretchingof the material-at the exteriorsurface.

When such linear consolidation hasbeen performed, vI bend or bring thelateral parts or leg 'portions'of the glank at-leach side-of such linearindentation toward each other into'angular formation with the apexoftheangle along the pre-.

'viously-consolidated line portion. The combination of interior-sideindentation with exteriorside consolidation having served to-rbring allthe blank material in this region :into .adense, strong, thin portionlocated at and near exterior surface,

.it becomes practicable to .accomplish such bending-With practicallycomplete absence of stretching or rupture of the exterior surface of thematerial along or adjacent to the apex line.

In performing the bending operation, I hold the-blanksolidly at the lineof first-consolidation, and bring the lateralor leg portions ef theblank on each side of such line toward one another into angularformation in such manner that each of these portions is keptsubstantially :flat or plane and will remain so in :the final product.

I nexthotpress the bent angular structure so produced, .and therebyobtaina final-angular fiber hardboard product which .is permanentlyconsolidated and densified throughout .(see Fig. 9). lt'isznotsnecessaryordinarily to chill the'finished product before it :is released fromconsolidating pressure and ittmay be released while hot. The thicknessof the finished product is less than about'50=%aof the thickness of thestarting blank.

Itv is tobe understood that the steps ;of the process maybe separate anddistinct, or may merge into one another in carrying out the productionof the product, particularly when done rapidly.

A final interior angle of 90 opening in the product is ordinarilydesirable for purposes such as mentioned below, but such angle may bemore than 90 or slightly less than 90 as may be called for (see Fig. 9).

With the use of relatively porous blanks made of hydrolyzed wood fiberproduced by treatment of wood chips with steam and explosive disruptioninto fiber, as by means of the gun described in U. S. Patent to Mason#1324221, and the resulting fiber somewhat refined, and its content ofwater solubles preferably reduced as by washing, formed into sheetscontaining about 2%-3% of preferably petrolatum for sizing purposes, anddried in a hot air drier without material pressure, the describedoperations can be performed and good sound products made without need ofaddition of other materials for bonding or plasticizing purposes. In thecase of using such blanks the linear consolidation and the bendingoperation and the later consolidation throughout are preferablyperformed at a die-temperature of about 200-220 C. If these blankscontain some moisture, as, say, about 5%-l0%, the pressure used inhot-pressing the bent blanks is preferably releasad one or more times topermit breathing or escape of vapors.

In case of blanks made of ground wood it is advantageous to add a smallproportion of resinous material, such as about l%30% of Vinsol forexample, since otherwise some rupture of the product may be caused atthe exterior and adjacent to the line of bending. Addition ofplasticizers, as about %-10% of moisture or a like percentage ofalcohol, is useful toward making good bends as described, and whenresinous material is incorporated, as Vinsol,

for example, it may be applied to the blank in an alcoholic solution. Incase of incorporation of such added binders, as Vinsol, for example,somewhat lower hot-pressing temperatures may be used, as about 150 C.for example. In case of using volatile alcohols for plasticizing,breathing is ordinarily unnecessary but may be resorted to if desired.

Use of wood fiber is preferred, and especially hardwood. However, woodymaterials of annual growth may be used as a source of lignocellulosefiber if desired.

My process can be performed without special apparatus or performed byapparatus of various kinds. In the accompanying drawings I haveillustrated one form of apparatus which can be used for carrying out mynew process, and also shown stages in the conversion of the blank to thefinal product.

In such drawings Fig. l is a side view partly broken away, and Fig. 2 anend view of an elongated press apparatus;

Figs. 3, 4, and 5 are transverse views with the elongated die bars inopen, partially closed, and closed positions respectively, andillustrating the blank and product in stages of the process as carriedout with the form of apparatus shown.

Fig. 6 is a transverse view showing use of weights instead of springs.

Fig. 7 is a transverse section of separate finishing dies, which may beused for effecting the final consolidation in a separate step or stage;and

Figs. 8 and 9 are perspective views with parts broken away of a partlyconverted blank and of a finished fiber-board product respectively.

The interior die bar I0 shown in the drawings of an elongated pressapparatus is adapted for use in making angular products having aopening. This die bar i0 is illustrated as being fixed and with otherparts moved up toward it, but other arrangements may be resorted to ifdesired. Provision is made for heating, cavities I 2 for steam or forelectrical heating elements or the like being indicated.

The exterior die arrangement consists of two die bars l4, l4 which arehinged together as by one thereof having at each end (one end onlyshown) a stud shaft i6 secured to it and extending through a journal [8in the second die bar of the pair. The axes of stud shafts iii are inalignment with the meeting edges of the upper faces of die bars l4, 14so that movement of the die bars [4, It takes place without anysubstantial opening being formed therebetween. The stud shafts l6, l6extend through slots 20 in brackets 22, thus permitting verticalmovement of die bars l4, 14 at their meeting edges. The die bars l4, (4are provided on their under sides with reenforcing" parts l4, 14' to bereferred to later. Die bars I4, M are supported near their outer edgeson ledges 24 at each side of the trough-like depression 26 in theheated, vertically movable press bar 28. The inner edges of die bars l4,ii are supported upon headed push rods 30 extending through bores inpress bar 28 and urged upwardly by springs 32. The springs 32 arepreferably enclosed in short tubular guards 33, attached to the heads 3!of push rods 30, and serving to prevent collection of foreign materialsby the springs 32. Various other means may be provided to perform thefunctions of springs 32. For example, Fig. 6 shows the weights 35 forthis purpose. Nuts 34 serve to limit the upward movement of push rods 30as shown in Fig. 3. Elevation of press bar 28 by the preferablyhydraulic rams 36 serves to bring the apparatus parts shown from theopen position shown in Fig. 3 to the position of Fig. 4, and to theclosed position of Fig. 5 respectively. Die bar in and press bar 28 arepreferably heatinsulated from adjacent bodies of metal as indicated at38.

With the parts in the position of Fig. 4, the lower part of blank 40which will be at the exterior of the product will be consolidated byheat and pressure along a longitudinal line 42 here shown as thelongitudinal center line of the blank, while the nose 44 of the interiordie bar Ill forms an indentation 46 in that face of the blank which willbe at the interior of the product. (See also Fig. 8). During thisoperation, the exterior die bars l4, 14 are supported by the springs 32so as to present a flat or substantially flat upper surface.

With further raising of the press bar 28, as indicated in Fig. 5, theexterior die bars l4, 14 will be forced to the closed position, springs32 being compressed and push rods 30 depressed by the major force of therams 36. At this stage, outside die bars l4, M will become substantiallyliners for the trough-like depression 26 in the press bar 28, with theirextending reenforcing parts [4, 14' being received in seats 26', 26'provided for that purpose. In this way said die bars l4, 14 are firmlyand solidly supported by press bar 28 to resist the application of thefinal consolidating pressure, are prevented from spreading apart oropening up, and are well heated from the internally heated press bar 28.The die bars may be directly heated if desired. When die bars l4, l4 arethus depressed by raising press bar 28, they form a female diecorresponding to the interior or male die bar 10.

With the parts in the position of Fig. 5, the final consolidatinghot-pressing operation can be completed with the production of afinished angular fiber-board product 38. However, if desired, thishot-pressing and consolidating oper ation may not be completed in theapparatus used for bending, and in such case the bent and partly-pressedangular product can be transferred to separate finishing press dies 10'and 50 (Fig. 7), and the hot-pressing completed by means of such dies I,58 if desired. In this way the bending press cycle can be considerablyshortened. The female die 58 may be made with a slight fillet, asindicated at so as to slightly round on the apex line if desired. If theblank 40 contains some moisture or other vapor-forming material, thepressure on the dies may be intermittently released in the early part ofthe operation of hot-pressing the previously bent blank to permitmoisture or vapor escape.

With my process, the hot-pressing consolidation is preferably appliedprogressively and gradually from the line 42 of first compactionoutwardly. This is accomplished with the apparatus shown by thedie-closing movement taking place against the resistance of the springs32 as will be readily understood.

Integral angular fiber-board products made from fiat sheet blanks inaccordance with my new process are strong and substantial, and arepractically free from breakage or cracking due to conversion fromoriginal flat blank formation to their final state. Being solidly heldbetween dies during the final hot-pressing operation, the final productshold their angular shape and are substantially free from tendency toopen or spread. Made smooth or with design impressed on surfaces on eachside, they are adapted for many uses, such as wall surfacing at eitherinside or outside corners, counters with integral backs, desks,furniture, and the like. It is a feature of great advantage that fiat orplane sheet blanks can be used and use of specially formed blanks isavoided since such fiat or plane blanks can be made on sheet-formingmachines at high speeds and with minimum expense.

The showing is for illustration only and not for limitation of myclaims.

The apparatus herein disclosed is claimed in Patent Number 2,431,353 andthe present application is a continuation-in-part of my co-pendingapplication Serial Number 547,211 now abandoned.

I claim:

1. Process of making an integral, angular hardboard product having aspecific gravity greater than 1 from a porous hydrolyzed lignocellulosefiber blank having a specific gravity less than 1, which comprisessupporting the entire area of theblank, hot-pressing a single grooveindentation in that side of the blank which is to be inside the productand thereby consolidating the blank material in the projected regionbeyond the groove to substantially its final thickness, bending theblank by applying increased pressure at elevated temperature at thegroove line while yieldingly supporting the entire area of the blankportions on each side of the groove and simultaneously partiallyconsolidating said portions by applying pressure gradually outwardlyfrom the groove whereby the final angularly product shape is formed, andthen finally consolidating said partially-consolidated portions of theblank to substantially the thickness of said projected region byapplication of high pressure and temperature.

2. Process as defined in claim 1, and wherein the thickness of theconsolidated angular product is less than of the original thickness ofthe porous blank.

ALVIE EVANS VARNER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

